PKC alpha is activated but not required during glucose-induced insulin secretion from rat pancreatic islets.
Diabetes
; 53(1): 53-60, 2004 Jan.
Article
en En
| MEDLINE
| ID: mdl-14693697
ABSTRACT
The role of protein kinase C (PKC) in glucose-stimulated insulin secretion (GSIS) is controversial. Using recombinant adenoviruses for overexpression of PKC alpha and PKC delta, in both wild-type (WT) and kinase-dead (KD) forms, we here demonstrate that activation of these two PKCs is neither necessary nor sufficient for GSIS from batch-incubated, rat pancreatic islets. In contrast, responses to the pharmacologic activator 12-O-tetradecanoylphorbol-13-acetate (TPA) were reciprocally modulated by overexpression of the PKC alpha WT or PKC alpha KD but not the corresponding PKC delta adenoviruses. The kinetics of the secretory response to glucose (monitored by perifusion) were not altered in either cultured islets overexpressing PKC alpha KD or freshly isolated islets stimulated in the presence of the conventional PKC (cPKC) inhibitor Go6976. However, the latter did inhibit the secretory response to TPA. Using phosphorylation state-specific antisera for consensus PKC phosphorylation sites, we also showed that (compared with TPA) glucose causes only a modest and transient functional activation of PKC (maximal at 2-5 min). However, glucose did promote a prolonged (15 min) phosphorylation of PKC substrates in the presence of the phosphatase inhibitor okadaic acid. Overall, the results demonstrate that glucose does stimulate PKC alpha in pancreatic islets but that this makes little overall contribution to GSIS.
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Bases de datos:
MEDLINE
Asunto principal:
Proteína Quinasa C
/
Islotes Pancreáticos
/
Glucosa
/
Insulina
Límite:
Animals
Idioma:
En
Revista:
Diabetes
Año:
2004
Tipo del documento:
Article
País de afiliación:
Australia